FIELD OF THE INVENTION
The invention relates to surgical drapes for maintenance of a surgical field and for collection of waste fluid.
Waste Fluid in Surgery
Irrigation fluid is commonly used in open surgery as well as in endoscopic examination and surgery performed on the vagina and uterus (transvaginally) and on the urethra and bladder (transurethrally). Any such anatomic approach requires sufficient dilation or spreading of the tissues to allow manipulation of the surgical instruments and to give the surgeon visibility to properly perform the surgery. In an anesthetized patient, clamps and/or retractors are used to maintain open surgical access and a weighted speculum is commonly employed to maintain the desired degree of vaginal dilation. A urethra is typically progressively dilated just prior to insertion of an endoscope guide tube.
Waste irrigation fluid drains at least intermittently from open surgical sites, as well as through and around the endoscope during transvaginal and transurethral endoscopic surgery. An intermittent or continuous flow of water-based (generally nonconducting) irrigation fluid from an external reservoir is directed to the surgical site by tubing, syringes, small containers or through the endoscope. Waste irrigation fluid drains, in turn, from the open surgical access, the vagina or the urethra.
Irrigation fluid flow in the area of surgery removes small pieces of excised tissue and blood, continually clearing the surgeon's view of the operative site(s). Most of the irrigation fluid which flows to the operative site is subsequently flushed out by additional irrigation fluid, but a portion of the entering fluid may be absorbed through the tissue surfaces of the operative site and through parts of the patient's vascular system exposed by the surgery.
During relatively prolonged and/or invasive surgery, sufficient fluid may be absorbed to substantially adversely alter the patient's serum electrolyte balance. Because serious electrolyte imbalances may result in seizures, coma or death of the patient, the surgeon must have sufficient warning of impending fluid overload to take corrective action. While this can be accomplished through frequent estimates of serum electrolyte levels during the surgical procedures, an easier and less expensive method involves estimation of the amount of fluid absorbed. In turn, this requires accurate estimates of the difference in the amounts of irrigation fluid administered and waste irrigation fluid lost. If blood loss can be accurately estimated or is clinically insignificant, the irrigation fluid difference can serve as an estimate of absorbed irrigation fluid. Errors in estimating the difference most often arise in estimating the amount of irrigation fluid lost because such fluid is typically hard to recover completely.
A fraction of the drained waste irrigation fluid typically falls on surgical drapes and thence to the operating table or floor, where it is commonly lost without being measured. Because the volume of this lost fraction of waste fluid is generally unknown, the amount of irrigation fluid absorbed by the patient is difficult to estimate accurately during the course of an operation.